[libcxx-commits] [libcxx] [libc++] Fix the handling of `views::take` for `iota_view` (PR #75683)

[A. Jiang via libcxx-commits]

https://github.com/frederick-vs-ja updated https://github.com/llvm/llvm-project/pull/75683

>From db8bbfc8b08673bb3c9637ea75071286c8f4ca48 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34 at live.cn>
Date: Sat, 16 Dec 2023 11:15:48 +0800
Subject: [PATCH 1/2] Fix the handling of `views::take` for `iota_view`

---
 libcxx/include/__ranges/take_view.h                         | 6 +++---
 .../std/ranges/range.adaptors/range.take/adaptor.pass.cpp   | 5 ++---
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/libcxx/include/__ranges/take_view.h b/libcxx/include/__ranges/take_view.h
index 518375d684abdd..d2764923fad366 100644
--- a/libcxx/include/__ranges/take_view.h
+++ b/libcxx/include/__ranges/take_view.h
@@ -290,16 +290,16 @@ struct __fn {
   constexpr auto operator()(_Range&& __rng, _Np&& __n) const
     noexcept(noexcept(ranges::iota_view(
                               *ranges::begin(__rng),
-                              *ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n))
+                              *(ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))
                               )))
     -> decltype(      ranges::iota_view(
                               // Note: deliberately not forwarding `__rng` to guard against double moves.
                               *ranges::begin(__rng),
-                              *ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n))
+                              *(ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))
                               ))
     { return          ranges::iota_view(
                               *ranges::begin(__rng),
-                              *ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n))
+                              *(ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))
                               ); }
 // clang-format off
 #if _LIBCPP_STD_VER >= 23
diff --git a/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp
index 8ffac8d8fab153..7c108bd5d0a9aa 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp
@@ -172,9 +172,8 @@ constexpr bool test() {
   // `views::take(iota_view, n)` returns an `iota_view`.
   {
     auto iota = std::views::iota(1, 8);
-    // The second template argument of the resulting `iota_view` is different because it has to be able to hold
-    // the `range_difference_t` of the input `iota_view`.
-    using Result = std::ranges::iota_view<int, std::ranges::range_difference_t<decltype(iota)>>;
+    // The second template argument of the resulting `iota_view` is same as the first.
+    using Result = std::ranges::iota_view<int, int>;
     std::same_as<Result> decltype(auto) result = iota | std::views::take(3);
     assert(result.size() == 3);
   }

>From 579ac915b3782f57b1f957e7d212dc8a7039c355 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34 at live.cn>
Date: Sat, 16 Dec 2023 11:29:00 +0800
Subject: [PATCH 2/2] clang-format off

The original indent seems intended.
---
 libcxx/include/__ranges/take_view.h                          | 5 +++--
 .../std/ranges/range.adaptors/range.take/adaptor.pass.cpp    | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/libcxx/include/__ranges/take_view.h b/libcxx/include/__ranges/take_view.h
index d2764923fad366..9e7e952eeb6710 100644
--- a/libcxx/include/__ranges/take_view.h
+++ b/libcxx/include/__ranges/take_view.h
@@ -278,10 +278,11 @@ struct __fn {
                               ); }
 
   // [range.take.overview]: the `iota_view` case.
+  // clang-format off
   template <class _Range,
             convertible_to<range_difference_t<_Range>> _Np,
             class _RawRange = remove_cvref_t<_Range>,
-            class _Dist = range_difference_t<_Range>>
+            class _Dist     = range_difference_t<_Range>>
     requires (!__is_empty_view<_RawRange> &&
               random_access_range<_RawRange> &&
               sized_range<_RawRange> &&
@@ -301,7 +302,7 @@ struct __fn {
                               *ranges::begin(__rng),
                               *(ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))
                               ); }
-// clang-format off
+
 #if _LIBCPP_STD_VER >= 23
   // [range.take.overview]: the `repeat_view` "_RawRange models sized_range" case.
   template <class _Range,
diff --git a/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp
index 7c108bd5d0a9aa..bb5b5f5ff4909a 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp
+++ b/libcxx/test/std/ranges/range.adaptors/range.take/adaptor.pass.cpp
@@ -173,7 +173,7 @@ constexpr bool test() {
   {
     auto iota = std::views::iota(1, 8);
     // The second template argument of the resulting `iota_view` is same as the first.
-    using Result = std::ranges::iota_view<int, int>;
+    using Result                               = std::ranges::iota_view<int, int>;
     std::same_as<Result> decltype(auto) result = iota | std::views::take(3);
     assert(result.size() == 3);
   }